On Tuesday afternoon she announced that her cancer had returned, and had spread to her back. She had initially postponed the tour, two weeks ago, with what she thought was sciatica.

“Olivia Newton-John is reluctantly postponing her June US and Canadian concert tour dates,” read a message on her Facebook page.

“The back pain that initially caused her to postpone the first half of her concert tour has turned out to be breast cancer that has metastasized to the sacrum.

“In addition to natural wellness therapies, Olivia will complete a short course of photon radiation therapy and is confident she will be back later in the year, better than ever, to celebrate her shows.”

Grease made the British-born Australian a household nameCredit:
Fotos International/Getty

"I decided on my direction of therapies after consultation with my doctors and natural therapists and the medical team at my Olivia Newton-John Cancer Wellness and Research Centre in Melbourne, Australia,” she said.

Newton-John had been touring her album LIV ON, which is a personal collection of songs about overcoming trauma - including her own battle with breast cancer in 1992, and the loss of her sister Rona to brain cancer in 2013.

“As a group, it's our intention with this album to create songs with a message of compassion and hope,” she said.

“They are for anyone facing a time of challenge in their life, whether it is grieving a loss or on the journey to health and recovery.”